Telephone receiver



Feb. 5, 1929.

N. C; SCHELLENGER TELEPHONE RECEIVER 2 Sheets-Sheet Filed Sept. 21, 1925 Feb 51 N. C. SCHELLENGER TELEPHONE RIfJCE I VER Filed Sept. 21, 1925 2 Sheets-Sheet 2 Patented Feb. 5, 1929. UNITED STATES 1,700,954 PATENT OFFICE.

NEWTON O. SOHEIILENGEB, ELKEABT, INDIANA, ASSIGNOB TO CHICAGO TELEPHONE SUPPLY COMPANY, OF ELKHABT, INDIANA, A CORPORATION OF DELAWARE.

TELEPHONE RECEIVER.

Application filed September 21, 1925. Serial No. 57,488.

The present invention relates to telephone receivers, particularly of the watch case type.

The watch case type of receiver is now generally used for radio reception. Forsuch uses the first requirement is sens tiveness and ability to talk clearly over a wlde range of fre uencies and degrees of loudness.

'e receiver should be light and yet mechanicall strong. It should be mexpensive to manu acture and it should present a good appearance.

The chief object of my invention is to roduce a receiver which shall meet thea 0ve requirements. In roducing such a receiver 1 I have made a num erof important improvements in receiver construction, chief of which are the followin 1. A shell 0 aluminum is drawn and threaded and thereafter the diaphragm seat is faced and trimmed radially to give an accurate clamping surface of exactly the right size. The side of the shell where the cords are introduced is marked with positive and negative signs so that no mistake may be made regarding the connection;

2. The permanent magnet is ade of two semi-circular halves lyin in substantially the same plane and restrained from outward movement by the containing shell and restrained from inward movement by the 1nterposed fastening bolt.

3. The pole pieces are rovided with mounting seats or bases slight y arched to insure a suitable clamping surface against the shell which will hold the pole pieces accurately and definitely in osition.

4. The terminals for t e windings are carried upon the bobbin heads in a novel manner.

5. The ends of the windings at the terminals are doubled back to insure good terminal conductivity and mechanical strength.

6. The upper heads on the bobbins, which are mounted on the pole pieces, are held together by the wire which connects the central terminal of both windings.

7. The upper heads of the bobbins are held on the pole pieces by notching the edges of the pole pieces, which notching expands the width of the upper ends of the pole pieces, this notching serving the dual purpose of holding the heads in place andof securing a better flux distribution. 0

8. The diaphragm is made of silicon steel.

9. The screws which hold the cup, the

magnet and the, pole pieces in assembly are provided with plain, flat heads which will not mar or scratch a finished surface, and these bolts are held against turning by fins which bite into the aluminum cup.

10. The terminal strip is. mounted on the screws which hold' the cup, pole pieces and magnet in assembly, and this strip is held on these bolts by a novel method of securing a nut or slug upon the bolt.

11. A novel terminal stripand connecting conductor are provided. In connection with this, a novel form of bolt and method of drawing up the same is provided.

There are other points of improvement which Wlll be apparent from the following detailed description of a specific embodiment of the invention.

Now, in order to acquaint those skilled in the art with the manner of constructing and operating a device embodying my invention, I shall describe in connection with the accompanying drawings a specific embodiment of the same. r 1

In the drawings:

Figure 1 is a vertical 'cross section through a receiver embodying my invention;

Fig. 2 is a horizontal section taken on the line 22 of Fig. 1, showing the magnet, pole pieces, and terminal strips in plane view;

Fig. 3 is a section taken on the line 3-3 of Fig. 1 at substantially right angles to the section of Fig. 1;

Fig. 4 is an isometric view of the finished cup or shell with the main mounting screws shown in position for the beginning of assembly;

Fig. 5 is a similar isometric view ofthe two' pole'pieces with bobbins and windings assembled thereupon. The parts shown in Fig. 5 are in position to be dropped into the shell shown in Fig. 4;

Fig. 6 shows the magnet as assembled in positlon ready to be dropped in on top of the pole pieces of Fig. 5;

Fig. 7 is a like isometric view of the two clamping washers or plates which pass over the bolts or screws shown in place 1n Fig. 4 to hold the magnet of Fig. 6 and pole pieces of Fig. 5 in place in the shell shown in Fig.4;

Fig. 8 is a like isometric view of the'two clamping nuts for the bolts aforementioned;

Fig. 9 is an isometric View of the terminal strip with terminal bolts thereupon;

Fig. 10 is alike isometric view of the slugs co-operate with the threads in the cap which are adapted to be. swaged upon the main bolts for holding the terminal strip of Fig. 9 in position;

Fig. 11 is an isometric view of the diaphragm which seats on top of the cup;

Fig. 12 is a like isometric view of the cap or ear piece;

Figs. 13, 14, 15, 16 and 17 are cross sectional views showing the different stages of manufacture of the aluminum cup or shell;

Fig. 18 is an exploded view of the pole piece and bobbin;

Fig. 19 is a cross sectional view of the upper bobbin head showing the manner of fitting the edges of the pole piece to retain the bobbin head in position;

Figs. 20 and 21 are detail elevational views showing the manner of forming reenforced terminals on the ends of the windings of the bobbins;

Fig. 22 is a plan view of a modified form of terminal strip and connection;

Fig. 23 is an enlarged cross sectional view taken on the line 23-23 of Fig. 22;

Fig. 24 is a plan view of one of the conductors mounted on the terminal strip for connecting the terminal bolts with the terminals on the bobbin heads;

Fig. 25 is a plan View and Fig. 26 an elevational view of the bolt or screw employed on the terminal strip;

Fig. 27 shows the slug assembled upon the terminal screw;

Fig. 28 shows the swaging of the slug upon the terminal screw; and

Fig. 29 is a fragmentary sectional view of a modified form of screw and slug assembly.

The receiver of my invention comprises an aluminum cup or shell 1 which has a cylindrical bead at its upper or free edge, this head being threaded, as indicated at 3, to 4. The rim or upper edge of the shell 1 has an inturned flange 5 which provides a seat 17 of definite radial dimension corresponding accurately with the radial dimension of the seat 18 formed on the bottom side of the receiver cap 4. The diaphragm 6, which is made of silicon steel. has a coating known as ferro type to avoid corrosion. This diaphragm is made of a steel known as silicon steel having a relatively high silicon content, and it performs in a manner far superior to a soft iron diaphragm such as has been heretofore known in the art.

It is highly desirable that the seats 7 and 8, between which the diaphragm is clamped, be of the same radial dimension so that there is no overlapping and hence deadening of the vibration of the diaphragm.

In making up the cup I first draw a fiat disc into the shape shown in Fig. 13, and punch the holes 9 and 10 for the main clamping screws, which will be referred to later, and also punch the holes 11 for admitting the conductors of the cord by which the receiver is connected to other parts of the circuit. The upper part of the cup is flared out, as indicated at 12 in Fig. 13. to form the flange portion 2 in the finished article.

Thereafter, the rim is turned in to form the flange 5, as shown in Fig. 14. This leaves the cylindrical surface 13 which is then threaded to form the threads 3, these threads preferably being rolled by suitable rolling cutter, since the metal of the shell is a soft aluminum. The turning inof the flange and the rolling of threads hardens the metal at these points.

Thereafter, the top surface of the inturned flange 5 is faced off, as indicated by the dotted lines 14 in Fig. 16, to form a flat finished seat 7 the radial extent of which is next accurately determined first by chamfering off the outer corner and then by boring out the flange 5, as indicated by the dotted lines 15 in Fig. 17. This forms the finished seat 7 for the diaphragm and, as above explained, the inner edge of the seat 7 accurately matches with the inner edge of the seat 8 on the cap 4.

The magnet system of the receiver comprises a pair of arcuate or substantially semicircular magnets shown in Fig. 6, these magnets 17 being identical in pattern and formed by punching the same out of sheet stock with an outer diameter of the finished magnet substantially the same as the inner diameter of the cup 1, a small clearance for assembly purposes being provided. The ends of the semi-circular magnets are notched out with round. substantially semi-circular notches 18, as indicated in Fig. 6, to fit relatively closely around the main clamping screws 20 and 21 which are shown in place in Fig. 4.

The notching of the ends of these magnets is not essential, but it serves to provide a larger area of contact between the ends of the magnets 17 and the corresponding bases 22 and 23 of the pole pieces 24 and 25. While I have shown only two solid permanent magnets 17, it is to be understood that the magnets may be made up of laminations which may be held in place as hereafter described.

The assembled pole pieces 24 and 25 with the windings and bobbins thereupon aredropped into the base of the shell 1 with the clamping bolts 20 and 21 in place, as shown in Fig. 4, the bases 22 and 23 of the pole pieces resting against the bottom of the cup. These bases 22 and 23 have suitable holes 26 and 27 fitting over the shanks of the bolts 20 and 21.

Fig. 18 shows in exploded View one of the pole pieces 25 with the bottom head 28 of the bobbin and the top head 29 of the bobbin adapted to be forced down over the pole piece 25, the bottom head resting down flat against the top of the base 23 and also resting against the extending lugs or legs 30, which are formed integral with the base 23. These legs an inch, so that in eflect three point contact is secured on the legs 30, 30 and on the extreme end of the base ad'acent the side walls of the cup 1. This arcing is beneficial in securing a substantially uniform seating of the pole pieces and a hlghl desirable accuracy of mounting. These age 30, 30 of the respective pole pieces extend toward each other, and they provide a minimum air gap between pole pieces for retaining the strength of the permanent magnets, as is disclosed in the co-pending application of Stirling, Serial No. 7 53,323, filed December 1, 1924.

After the heads 28 and 29 are in place on the pole piece such as 25, a wrapping of paper, as is indicated at 31 in Fig. 19, is applied to the pole piece between the bobbm to avoid accidental short circuit or grounding between the winding and the frame of the i ftz th 1 i h F 5 r e ep1eces,assown1n 1g.,

are assembled on the bolts and 2-1 in the cup 1, as shown in Fig. 4, the magnets 17, 17 are then dropped into the shell 1, the notches I8, 18 embracing the bolts 20 and'21, and then the clamping plates 32, which have suitable holes 33 therein, are drop ed down over the bolts 20 and 21 to'hold t e ole pieces and magnets firmly in clamped position against the face of the shell, suitable pres sure being applied by the threaded nut 35, shown in Fig. 8. g

It is to be observed that the outer edges of the plates or washers 32 are formed on an are, as indicated at 36, and this are is substantially the same as the curvature of the inside of the shell 1, so that the plates 32, 32 are held against turning as the nuts 35 are drawn tight. These washers 32, 32 are preferably of aluminum forthe dual purpose of lightness, and also to permit them to be squeezed into intimate keying contact with the. ends of the magnets.

These washers 32, 32 may be made of soft iron if desired,-or they-may be made of fiber or other suitable material.

Their chief purpose is to serve as suitable securing means for clamping the magnets against the pole pieces and the pole pieces against the bottom of the cup. It is to' be observed that since the magnets 17, 17 fit closely within the cup 1, they cannot escape outwardly or endwismbecause they fit against the iner walls of the cup. They cannot move towards each other because the screws 20 and 21 serve as s acing means between them.

The upper head 29 of the bobbin which is thus formed directly on the pole piece, such as 25 shown in Fig. 18, has extending lugs 38 and 39, as shown in Fig. 18, for supporting and mounting the ends of the windings on the respective pole pieces. That is to say, the center terminal of the winding is brought out and mounted on the lug 39, and the end terminal of the winding is brought out and wrapped around the lug 38. The manner of bringing out these terminals of the windings and mounting them upon the lugs is illustrated in Figs. 20 and 21. The Wire which is wound upon these bobbins is a fine enameled wire, this wire being indicated at 40 in Fig. 20. The outer end of the wire is stripped of its insulating cover to leave the bare conductor, indicated at 41 in Fig. 20. A suitable length of the conductor is thus bared and then it is folded back upon itself, as indicated at 42 in Fig.21, and the free end is then Wrapped a number of times about the insulated portion 40, leaving a double thickness 43 which is wrapped around the corresponding terminal 38 or 39, as the case may be, and it is tinned in-place so that in reality the convolutions which are wound upon the terminals 38 and 39 are soldered together. Thus, each pole piece, bobbin and winding is self contained and has its terminals brought out in a permanent manner without danger of injury. The terminals of the wire are thus reenforced so that in the tinning operation and, in fact, during the wrapping operation there is no danger of the wire being broken, as by oxidation or mechanical injury,

and likewise so much of the wire as is unsupported by being closel wrapped upon the bobbin is of double thickness and hence of double strength.

The upper head 29 is held in place upon the corresponding pole piece as, for example, 25 shown in Fig. 19, b splitting the edges of the pole piece as in icated at 44 in Fig. 19. This splitting of the edges of the pole piece secures the double result of first, securely holding the head 29in place as by riveting. Next, there is an important magnetic effect from thus spreading out the pole piece, name- 1 to prevent the concentration of flux atthe sliarp corners of the pole piece. The top of the pole pieces are carefully ground oil to provide the correct air aps between the ends of the pole pieces and t e diaphragm 6, and this always tends to leave a sharp corner where the magnetic flux concentrates and produces an undesirable efi'ect. By my invention of splitting and bending over the portion 44 of the pole piece, I secure an effect which is that of preventing sharp concentration at the corners of the pole piece in a manner somewhat similar to chamfering these corners, but of a better characteristic in that the pole iece is thereby in effect widened instead 0 being made narrower, and at the same time the flux concentration at the corners is prevented.

The bolts 20 and 21, which assemble the magnet structure and the terminal strips later to be described, have fiat button heads as indicated at 45 (see Figs. 1 and 3), these heads on their exterior being smooth and being carefully rounded so that they will not scratch a finished surface such as the top of a desk or the like.

To prevent these screws from turning I provide them at the junction of the head and the shank with small triangular webs or fins 46, which may be three or more in number. They extend longitudinally only a short distance so as not to extend beyond the inner edge of the bottom of the cup 1. Their purpose is to bite into the metal of the bottom of the shell surrounding the bolt holes 9 and 10 to anchor themselves firmly against turning, so that a screw driver slot in the head will not be necessary. This permits the head 45 to be made thin and flat. presenting a very attractive appearance and avoiding injury to finished surfaces such as a varnished desk top, or the like. When the nuts 35 are drawn down tight on the bolts or screws 20 and 21, there is a tendency to spring down the bases 22 and 23 of the pole pieces flat against the bottom of the cup and, at the same time, the bolts are caused to engage, by means of the webs 46. with the metal surrounding the holes 9 and 10 to prevent the bolts from turning. Also, the plates 36 are forced down upon the top of the magnets 17 tending to hold these magnets and the bases of the pole pieces firmly in engagement.

The terminal strip is a thin piece, preferably of fiber or other suitable tough insulating material of generally semi-circular configuration, this strip extending slightly beyond the diameter so as to provide stock for the bolt holes 51, which bolt holes are adapted to pass over the tops of the bolts 20 and21 011" mounting the terminal strip 50 upon said A suitable lock washer and nut may be employed for clamping down the ends of the terminal strip 50, or instead of the same I may employ the soft metal slugs 52, 52 shown in Fig. 10, these slugs being pressed down and swaged into the threads of the bolts 20 and 21 in a manner to be described more fully later. In such case the slugs 52 are preferably made of soft aluminum, and they are merely dropped over the ends of the bolts 20 and 21 and then by means of a swaging tool, such as shown at 53 in Fig. 28 the slugs are shrunk or swaged by mechanical pressure or a succession of sharp blows onto the corresponding bolts. It will be apparent also that instead of employing the clamping nuts 35, similar slugs may be shrunk or swaged in place above the washers 36 to hold the magnet system in assembly.

The terminal strip 50 bears a pair of terminal screws or bolts 54. 54, these screws having button heads 55 as indicated in Figs. 25,

26, 27 and 28, with radial fins 56 formed upon the under side of the head next to the shank of the bolts, such fins 56 being adapted to be pressed or drawn into the body of the insulating strip 50 to prevent turning of the terminal bolts or screws 54. These screws 54 may be secured upon the strip 50 b the usual threaded nuts, such as theones s own at 35 in Fig. 8, but I find that assembly is greatly facilitated by the aforementioned method of employing a slug 57 of soft metal, such as aluminum, which may be quickly swaged upon the bolt and, at the same time, the bolt drawn tight by said swaging action.

In Figs. 1, 2 and 3 and particularl in Fig. 9, I have shown one method of providing connection between the terminal screws 54 and the terminals of the socket winding by passing terminal wires 58 through suitable holes in the terminal strip 50 and soldering the lower ends of said wires 58 to the heads 55 of the screws 54, as indicated at 59 in Fig. 3. As a matter of convenience in assembly, the lower ends of the wires may be wrapped around the shank of the bolt just above the head 55 and squeezed into the material of the strip 50 by the swedging of the slugs 57 thereupon.

In Figs. 22, 23, 27 and 28 I have illustrated the preferred method of forming the terminal connection, namely, by the use of stampings of thin soft sheet copper of the form shown in Figs. 24 and 25 and indicated by the reference numeral 60. These stampings 60 comprise a lug 61 in which there is formed a suitable hole 62 adapted to fit over the bolts 54 on the top side of the terminal strip 50, as is shown in Figs. 22 and 23, and also indicated in section in Figs. 27 and 28. Thereupon the soft slug 57 is laid on top of the lug 61, and the swaging tool 53 which has a conical socket adapted to fit over the edge of the slug 57 is brought down, and either by direct pressure or by a series of shar blows this swaging tool 53 presses the slug 57 down on top of the lug 61, a suitable support being provided for the head 55, so that the bolt is drawn tight against the bottom of the strip 50 while the slug 57 is pushed down axially and .compressed radially to give a riveting action.

I find that slugs such as 57 may be very quickly and solidly swaged upon the shanks of the bolts 54 with much less labor and inconvenience than is required to thread corresponding nuts down on the shanks of the bolts and to draw them tight. The fins 56 anchor themselves firmly in the material of the strip 50, and these bolts are anchored securely and permanently to the body of the strip 50. Excellent electrical contact is also made between the strip 60 and the terminal bolts 54 by the aforesaid method of assembly.

The threads of the screw 54 in this case perform the dual function of providing suitable shoulders which the slug 57 may engage to prevent relative endwise motion and also provide co-o erating threads for the nut 66. Now it is to observed that the slug ma be shrunk or swaged u on a suitable shoulder to hold the slug on t e bolt against endwise motion that is to hold the parts under the slug tight, which shoulder need not be a part of the threaded shank of the bolt.

-In Fig. 28 I have shown the bolt 54" as having a shoulder 70 formed b a in the shank of the bolt. T e s u 57 is swaged into the ove 71 and is hel by the shoulder 70 agalnst upward motion. It is also held a inst downward motion. Obviously, the s oulder might be formed square, tapered, or otherwise, and it might be formed continuous, as shown, or interrupted as by knurling, as will at once be appreciated by those skilled in the art. Also, instead of having the shoulder or projection lie within the periphery of the shank of the bolt, it might lie outsi e of the same or part1 outside and part1 inside. I find it convenient to thread the s ank of the bolt and use the lower part of the threads for the slug and the upper part for the nut, but do not intend to be limited to such form only. I

I consider this method of assembling a bolt and a formed nut as an important part of the present invention. The terminal strip 60 then passes directly to the lugs 38 on the bobbins 29,- where the free ends of said strip may be wrapped around said lugs over the tinned termmals of the windin and with a touch of the soldering iron a electrical and mechanical connection may be made at this point.

The center terminals of these coils are connected by wrap ing a wire about the two lugs 39 and drawing it tightly about the same for the double purpose 0 securing good con- J tact with the terminals of the wires which rest upon said lugs 39, and also for holding mechanically the top of the bobbins in engagement. A touch of the soldering iron then rmly'unites such tie wire with the terminals of the winding on the lugs 39 and the electrical connection from the screws 54 to the windin is complete.

e flexible cord having the two strands 63 and 64, as shown in Fig.2, with suitable forked or eye terminals thereon are then hooked over the bolts 54, and suitable hexagon clam ing nuts 66 are then threaded down upon sai terminals to hold the same in p ace.

It will be apparent that a swaged nut, such as indidated at 57 might be employed on top of the terminals 6 but I prefer to use hexagon nuts or other preformed clamping means cause it is desirable to permit the terminals to be connected or disconnected readily for re air urposes. However, it is not desirable at t e sw (1 nuts 57 be released, since they are intende to be permanently attached oove 71 i to the bolts 54, and since they are left substantially round and of conical shape they are not easily disturbed by the curious investigator who opens the receiver. The same thing is true of the swaged nut 52 which clamps the terminal strip 50 in place, since there is no convenient hold upon the same, there is less likelihood of distur ance through idle curiosity.

In fact, I may prevent turning of the slug 57 by roviding a longitudinal'score or key on the olts 20 and 21 and also upon the bolts 54, so that whenthe nuts such as 52 and 57 are swaged in place the? will be held not only against lon 'tudina movement by the threads, but the orcing of the metal into the key or score will prevent rotational movement.

Preferably, the terminals 65 are covered either by a wrapping of thread or by an extermion of the acket of the ,cord to such a point that there is no tendency for either conductor 63 or 62 to ground u on the shell 1.

I do not intend to be limits to the details shown and described, exce t as the same ma be recited in the appende claims, as it w be apparent to those skilled the art that numerous changes embodiment may be made without departing from the true scope of my invention.

I claim:

1. In a telephone receiver, the combination of a cup having a flat bottom port1on, a pole piece comprisin a base portion and an n right ortlon, t e base portion of sa1d po e iece ing'arched, and means to clamp sa1d ase against the bottom of sa1d.cup.

2. A air of magnets for a telephone receiver aving a relatively semi-circular sha e and provided with erally U-shaped ends to rmit means for astening the magnet in t 0 receiver to extend therebetween.

3. In a device of the class described, a pair of arcuate magnets placed end to end in substantially the same plane notches in the adjacent end of said magnet, clam ing means clampm means and being ,dis osed between,

said no es in the adjacent en s of the magnets and circumferentially restraining m'eans about the magnets;

4. A ole piece comprising a stamping; magnetic sheet material com IlSlIlg a portion and an upright portion, said base portion being wider than t e upright portion and havin integral lugs extending m substantially t e plane of the base portion beyond the junction of the base portion and the upright ortion, said base ortion between the ends of sa1d lugs and t e opposite extremity with a p aner supporting surface at opposite ends of said base.

being arched to provide contact 5. In a device of the class described, a pair of parallel pole pieces having bobbin heads of insulating material at the free ends of the pole pieces, said heads being of generally oblong formation and having each integral extending lugs, one on each end of the corresponding head, said heads being substantially in contact, the lugs on one side extending in parallelism from the adjacent edges of the heads, the lugs on the other side of the heads extending at substantially right angles to the first lugs.

6. A bobbin head comprising a generally oblong plate of insulating material having integral lugs, one of said lugs being formed as an extension of a longer margin of the plate and the other being formed as an extension of the shorted margin of the plate.

7. A bobbin head comprising a generally oblong plate of insulating material having integral terminal lugs, one of said lugs extending outwardly along a longer margin of the plate and the other lug extending from the plate at right angles to the line of the first lug.

8 In combination, a pair of flat parallel pole pieces, bobbin heads upon the ends of said pole pieces, said bobbin heads comprisingdplates of generally oblong outline, each hea having a first lug extending out along the inner margin thereof and having a second lug at right angles to the line of the first lug, a winding on each bobbin, said. windings being anchored upon said lugs by wrapping the ends thereof about the lug and soldering the wrapped ends, said lugs along the inner margins being tied together mechanically by a tie wire wrapped around the same and the adjacent ends of the windings being electrically connected by said tie wire.

9. In a telephone receiver, a fiat pole piece, a bobbin head of insulating material adjacent the end of the same, and a diaphragm supported beyond the end of the pole piece, said pole piece having diagonal ears split off of its edges, the ends of said ears lying below the tops of the poleupieces and serving to prevent undue concentration of magnetic flux at the corners of said pole pieces.

10. In a telephone receiver, an angular pole piece comprisin a sheet metal stamping of magnetic materlal, said pole piece having a base and an upright portion, the base portion being wider than t e upright portion and having integral In S extending in the plane of the base portion eyond the junction of the base portion and the upright portion, a lower bobbin head embracing the lower end of the upright portion and resting against said base and said lugs, and an upper bobbin head embracing the upper end of the upright portion, the face of the upright portion being split adjacent the edges to form laterally extending lugs serving tohold the upper bobbin head in place and to prevent flux concentration.

11. In a telephone receiver, an angular pole piece comprising a sheet metal stamping of magnetic material, said pole piece having a base and an upright portion, the base portion being wider than the upright portion and having integral lugs extending in the plane of the base portion beyond the junction of the base portion and the upright portion, a lower bobbin head embracing the lower end of the upright portion and resting against said base and said lugs, and an upper bobbin head embracing the upper end of the upright portion, the face of the upright portion being split adjacent the edges to form laterally extending lugs serving to hold the upper bobbin head in place and to prevent flux concentration, said upper bobbin head having an integral lug extending therefrom in a direction at substantially right angles to the base portion, and a second integral lug extending in a direction substantially at right angles to said first lug.

12. In a receiver, a cup having a cylindrical wall and a substantially fiat bottom wall, angular pole pieces having their bases mounted on the bottom wall of the cup, bolts arranged diametrically in the bottom wall of the cup, said bolts passing through said pole pieces, semi-circular magnets having their ends lying on said bases of the pole pieces with said bolts between adjacent ends of the magnets, clamping means for clamping said magnets and pole pieces upon the bottom of the cup by means of said bolts, an arcuate terminal strip of insulating material lying within the cup and having its ends held by aforesaid bolts, said pole pieces having upright portions with bobbin heads upon their upper ends, said bobbn heads having terminal lugs disposed adjacent to each other and extending in the same direction, windings on said pole pieces having their center terminals mounted on the aforesaid lugs, said bobbin heads having integral lugs extending at right angles to the direction of the aforesaid lugs for receiving the outer ends of the windings on said pole pieces, terminal screws mounted on said arcuate strip, and conductors connected at their outer ends to said screws and at their inner ends to the last named terminal lugs.

13. In combination, a pair of pole pieces having bases and uprights, a pair of arcuate magnets lying in substantially the same plane, diametrically arranged posts lying between the ends of the magnets and extending through the bases of the pole pieces, means on the bolts for clamping said bases and said magnets together, an arcuate terminal strip having its end passed over said posts, means for holding said ends on said bolts, terminal screws mounted on said arcuate terminal strip, bobbin heads on the uprights of the pole pieces, integral lugs extendin out laterally from said bobbin heads, ar connecting conductors extending from said terminal lugs to the terminal screws.

14. In combination, a pair of pole pieces having bases and uprights, bobbin heads on the uprights, said bobbin heads having lugs extending adjacent each other, windings on the pole pieces having their inner end wrapped about said lugs, a tie wire embracing said lugs and connecting the inner ends of the windings, other terminal lugs extending out laterally from the bobbin heads, the external ends of the windings being wrapped about said lugs, a terminal strip supported adjacent said bobbin heads, said terminal strip having terminal screws, connecting conductors comprising thin ribbons of copper having their outer ends connected to said terminal screws and having their inner ends wrapped about the laterally extending lugs to make contact with the external terminals of the windings.

In witness whereof, I hereunto subscribe 20 my name this 17th day of September, 1925.

NEWTON C. SCHELLENGER. 

